Study On Reversible Data Hiding Technology And Its Application In Ruboust Watermarking

With the fast development of internet and the extensive application of digital media (digital image, digital audio and digital video), the multimedia communication has become the important way of information exchange among peoples. Because digital media has become increasingly easy to be copied and widely disseminated, which bring convenience to people, but also the digital information can easily be stolen, tampered with, illegal copying and dissemination, and which had bring a negative effect on the information industry. Digital watermarking is a technique which is a effective way used in copyright protection and information security. In this paper, reversible information hiding, and robust digital watermarking method based on the reversible information hiding are mainly studied theoretically and experimentally, the main work of the paper is as follows:(1)The reversible data hiding methods of difference expansion and histogram modification are analyzed and the merit and demerit is also presented, and that the method of difference expansion is a particular case of the method of histogram modification is proposed. Furthermore, the paper presented that if the element of the inverse of transformation matrix is all integer, embedding message in the transform domain based on the already existing reversible data hiding method can achieve reversible information hiding, and the experiment also prove the theory. (2) In the research field of reversible data hiding, Reversible data hiding method based on sorting and histogram modification is proposed. The cover image is firstly divided into non-overlapped blocks, and the pixels in blocks are sorted. According to the sorting result, the medium value is selected as the reference value while is used in calculating the difference values among all the pixels values in the block. The reversible data hiding method of histogram modification is used for embedding secret data in the difference values. In the proposed method, the medium value is act as a reference value, So the histogram of difference values is more compact, and the peak point is larger, and the method can achieve higher capacity. Furthermore, a high-capacity reversible data hiding based on histogram modification and prediction is presented. In this method, the difference image which is calculated by the predictor is almost as the same size as the original image, so the method is make full use of the similar pixel value of the adjacent pixels. The difference image is firstly calculated between a pixel and its predictive value, and then the secret data is embedded in the cover image by modified the histogram of the difference image. Furthermore,The multilevel embedding is also used in the scheme to achieve reversible data hiding with high embedding rate.For solving the contradiction between robust and the nonvisibility of the existing robust digital watermarking, a new framework model of robust digital watermarking based on reversible data hiding is proposed. In this model, the watermark is firstly embedded in the cover image by the robust watermarking scheme, and the information to recover the cover images is hiding in the watermarked image by the reversible data hiding method. The robust of scheme based on the model is determined by the robust watermarking scheme in the first embedding, and can recover the cover data losslessly or near-losslessly. Based on the framework model, two specific methods are proposed. One of the specific methods is the robust digital watermarking method based on reversible data hiding and JPEG. In the proposed method, the scrambled watermark is embedded into the in the least signification bits (LSB) of the low frequency coefficients, and which coefficients the watermark embedded into are determined by the chaos operator. In the last, the information to recover the cover images is embedded in the high frequency coefficients by LSB substitution by reversible data hiding method. The other specific method is the near-lossless robust digital watermarking based on SVD and reversible data hiding. The watermark is firstly partition the host image into non-overlapping blocks,and the watermark is embedded in the U component after the SVD transformation is performed on the blocks. Secondly, the information of recover the cover images is hiding in the watermarked image by reversible information hiding method. this scheme can recover the cover image near-losslessly.